This invention relates to impact testing and more particularly to a computerized simulator and method for determining the effects on cargo during a railroad car humping.
The coupling of rail cars is commonly referred to as a humping. During a humping of railroad cars, cargos are subjected to high inertia loads. If their containers and/or shipping provisions are inadequate, damage can occur, resulting in insurer losses and higher consumer prices. Simulators exist for evaluating the effects on cargo and their containers of humping. They rely on the deformation of rubber, plastic, springs, weights, etc. to rapidly decelerate the cargo. Tests show that the simulators do provide meaningful results for preventing damage and optimizing shipping provisions and containers. Consequently, producers and shippers must rely on actual experiences which are often costly and detrimental to customer goodwill. Moreover, many containers and shipping provisions are inadequate or more costly than necessary. A further problem with existing simulators is that they cannot be easily modified to simulate alternate levels of severity of rail car humping.
Turczyn, U.S. Pat. No. 4,545,236 is exemplary of existing rail car humping simulators. Turczyn discloses a cargo, carried on a sled, which is accelerated by gravity down an inclined plane. At the bottom of the plane there is a deformable cylinder which decelerates the sled and its cargo. The dynamic crush properties of the deformable cylinder are established from accelerometers mounted on railroad cars. After each test, the deformable cylinder is replaced.
The present invention completely overcomes problems and shortcomings of existing simulators by providing an efficient, easy to use, computerized apparatus and method for simulating railroad car humping. The invention resides in features which individually and collectively contribute to its ability to efficiently and reliably replicate inertia loads on cargo during xe2x80x9chumping.xe2x80x9d One advantage of the invention is that a manufacturer can reduce the time for developing adequate provisions for shipping a new product. Another advantage is that test conditions can be easily modified to vary levels of severity. Another advantage is that test results can be quickly obtained. Still yet another advantage is that test results are repeatable. Still yet another advantage is that test results correlate substantially better with real world conditions than those of simulators heretofore available.
The invention broadly comprises a twelve-wheel test cart mounted on a pair of rails; an impact structure for simulating rail cars which are coupled to the test cart; a means for propelling the test cart toward the impact structure, a means for decelerating the test cart during a humping of the test cart with the impact structure; and a programmable computer for controlling the test. Preferred means are disclosed for accelerating and decelerating the test cart during the simulated humping.
Further objects, benefits and features of the invention will become apparent from the ensuing detailed description and drawings which illustrate and describe the invention. The best mode which is contemplated in practicing the invention together with the manner of using the invention are disclosed and the property in which exclusive rights are claimed is set forth in each of a series of numbered claims at the conclusion of the detailed description.